Compressor Housing of a Radial Compressor

ABSTRACT

A compressor housing ( 16 ) of a radial compressor at least two housing portions ( 10, 12, 14 ) at least partially of plastic material and defines compressor impeller installation space ( 48 ) and a spiral duct ( 46 ) that surrounds it radially on the outside with regard to a rotational axis ( 18 ) of an impeller. A securement structure ( 50 ) encloses the compressor impeller installation space ( 48 ) at least partially in an annular manner and is arranged in radial direction between the impeller installation space ( 48 ) and the spiral duct ( 46 ). The securement structure includes a separate burst-protection ring ( 50 ) with a tubular wall section ( 34 ) enclosing the impeller installation space ( 48 ) circumferentially.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 USC 119 to German PatentApplication 102011017052.9 filed in Germany on Apr. 14, 2011, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a compressor housing of a radial compressor, inparticular of a turbocharger of an internal combustion engine, inparticular of a motor vehicle, with at least two housing componentsconsisting at least partially of synthetic material, wherein acompressor impeller installation space and a spiral duct surrounding itradially on the outside with regard to a rotational axis of a compressorimpeller are provided, and a securement structure enclosing thecompressor impeller installation space at least partially in an annularmanner is disposed in radial direction between the compressor impellerinstallation space and the spiral duct.

BACKGROUND OF THE INVENTION

A radial compressor housing in particular for a turbocharger featuringat least two housing components is known from WO 2009/065881 A1. Acompressor impeller installation space and a spiral duct are provided.The housing components are made of synthetic material. The radialcompressor housing can be made of synthetic material in an easy andcost-effective way. The wall thicknesses can be optimized depending onthe material used and the weight. Radial compressors have to guaranteean adequate operational safety. Due to the high impeller speeds ofturbochargers there is a risk that, when the compressor impeller isdamaged, metal shards penetrate the housing of the compressor and damagecomponents in the engine compartment of the internal combustion engine.To avoid this, a securement structure encloses the compressor impellerinstallation space partially in a ring-shaped manner. The securementstructure is undetachably connected with one of the housing components.The securement structure consists of a plurality of ribs which areintegrally molded to an exterior side of an external wall surroundingthe compressor impeller installation space. If parts break away from thecompressor impeller, stiffening measures of the ribs shall prevent thehousing from being penetrated.

SUMMARY OF THE INVENTION

An objective underlying the invention is to design a compressor housingas mentioned above that can be manufactured easily and which is robust.It should be optimized with regard to the material used and the weight.Furthermore, the operational safety shall be enhanced particularly inthe case when parts break away from the compressor impeller.

This is solved according to the invention by the fact that thesecurement structure features a separate burst-protection ring with atubular wall section enclosing the compressor impeller installationspace circumferentially and which is disposed in the compressor housingand fixed in its position.

According to the invention, a burst-protection ring is thereforeprovided with a tubular wall section that encloses the compressorimpeller installation space circumferentially in a closed manner. Thus,the wall section forms circumferentially a preferably completeprotection that prevents in particular parts breaking away from thecompressor impeller from penetrating radially to the exterior. Theseparate burst-protection ring can be in particular optimally adapted tothe shape and/or size of the compressor housing. The burst-protectionring can also be optimized for different requirements of the radialcompressor with regard to its shape, size and/or material. For example,radial compressors can be designed for higher compressor impeller speedsthan with known compressor housings made of synthetic material which aresubjected to corresponding higher loads. As the burst-protection ring isdisposed between the compressor impeller installation space and thespiral duct, it does not expand towards the exterior. In this way, theinstallation space needed for the compressor housing is smaller.Furthermore, the burst-protection ring cannot be seen from the outsidewhich is optically appealing. The separate burst-protection ring can bemade of the same material as the compressor housing, or it can be madeof other materials. The tubular shape of the burst-protection ringstabilizes the compressor housing. It furthermore enhances thedisruptive strength. A burst-protection ring which is realizedseparately from the housing components simplifies the manufacture of thehousing components unlike the compressor housings known from prior artwhere the housing components must be equipped with complex shapes thatform the safety structure. During installation, the burst-protectionring can simply be connected with one of the housing components beforethe housing is closed with the second housing component during assembly.When connecting the housing components by ultrasonic welding, theseparate burst-protection ring can influence positively the developinginherent vibrations. Advantageously, the burst-protection ring dampensthe inherent vibrations. As the burst-protection ring is fixed in thecompressor housing in its position, this further enhances the stabilityof the compressor housing. Furthermore, rattling of the burst-protectionring is prevented during operation of the radial compressor. Theburst-protection ring in conjunction with the circumferential wallsection ensures an additional stability against a radial expansion ofthe wall surrounding the compressor impeller installation space. Thedeveloping heat during the operation of the radial compressor can causea stronger expansion of the synthetic material of the compressor housingthan of the material of the compressor impeller. If the compressorimpeller is in particular made of metal, its thermal expansion is lowerthan that of the compressor housing made of synthetic material. Due tothe different expansion, the radial distance between a radial outer sideof the compressor impeller and a radial inner side of the wall, whichdefines the compressor impeller installation space, can be enlarged.This may result in a reduced efficiency of the radial compressor. Theburst-protection ring can prevent the compressor housing from beingradially expanded. In this way, the efficiency is less affected when theradial compressor is heated up. Advantageously, the burst-protectionring is made of a material that can absorb the kinetic energy generatedby fractions possibly thrown off the compressor impeller. The compressorhousing made of synthetic material in conjunction with theburst-protection ring can under severe stress pass a burst-protectiontest, also known as containment test, than conventional compressorhousings made of synthetic material. The burst-protection ring can alsobe called containment ring.

In an advantageous embodiment, the burst-protection ring may be disposedin an annular space surrounding the compressor impeller installationspace radially outside and which is defined by at least two of thehousing components. The annular space may preferably be accessible fromthe outside prior to the assembly of the housing components. This makesit easy to introduce the burst-protection ring into the annular spaceduring the assembly of the compressor housing. It can also be securedagainst loss at one of the housing components. When assembling bothhousing components, the annular space may be closed. This makes it easyto fix the burst-protection ring in the annular space. Additionalfasteners are not required. The separate burst-protection ring may bedisposed advantageously in an annular space which already exists in thecompressor housing.

Advantageously, the burst-protection ring may be fixed in the compressorhousing by means of a form-fit connection, in particular by clampingribs and/or snap-in hooks and/or beads, and/or by means of a force-fitconnection, in particular by pressing on or by pressing in theburst-protection ring, and/or by means of a cohesive connection, inparticular by a glued connection, an injection connection or a weldedconnection. Such connections make it possible to fix theburst-protection ring easily, reliably and in a stable manner in thecompressor housing. Before assembly of the housing, the burst-protectionring can be easily fixed by means of the connection at one of thehousing components. Thus, it is easy to realize a loss preventiondevice. Both housing components can then be connected with each other.Form-fit connections can be easily realized in particular by connectingbars and grooves which can cooperate in a form-fit manner when insertingor placing the burst-protection ring on a corresponding housing part. Inparticular, clamping ribs and/or snap-in hooks and/or beads that alreadyexist in the compressor housing can be used. Form-fit connections can beeasily realized in a stable manner. If required, they can be loosenedagain easily. The advantage of force-fit connections is that they can berealized easily and in a stable manner. Additional connection componentssuch as, in particular, ribs, snap-in hooks or beads at theburst-protection ring and at the corresponding housing component are notrequired. The manufacturing costs for the burst-protection ring and thehousing components can be reduced accordingly. Cohesive connectionsallow to realize easily an additional sealing function. Cohesiveconnections enable in particular to seal easily gaps between theburst-protection ring and the corresponding housing component.

Furthermore, the burst-protection ring can advantageously be made atleast in the wall section of a ductile material, in particular metal,synthetic material, carbon fibers, ceramics, aramid fibers or a materialmix. Ductile material can feature a high impact strength, a highelongation at break and/or a high vibration damping. Ductile materialcan give the burst-protection ring, in particular the wall section,optimal characteristics with regard to elasticity, ductility, anddeformability. In this way, the burst-protection ring can easily andreliably absorb the energy of thrown-off fractions. It can thus preventfractions from penetrating.

In another advantageous embodiment, the burst-protection ring can atleast participate in forming a wall section of the spiral duct. In thisway, the burst-protection ring can participate in designing one part ofthe flow contour in the spiral duct. The housing components and theburst-protection ring can be assembled in a modular way to form thespiral duct. The flow contour in the spiral duct can be optimized by theshape and/or size of the burst-protection ring. Furthermore, theburst-protection ring can enhance the stability of the walls of thespiral duct.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying Figures, where like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which together with the detailed description below are incorporatedin and form part of the specification, serve to further illustratevarious embodiments and to explain various principles and advantages allin accordance with the present invention.

Features of the present invention, which are believed to be novel, areset forth in the drawings and more particularly in the appended claims.The invention, together with the further objects and advantages thereof,may be best understood with reference to the following description,taken in conjunction with the accompanying drawings. The drawings show aform of the invention that is presently preferred; however, theinvention is not limited to the precise arrangement shown in thedrawings.

FIG. 1 is a schematic axial cross section of a compressor housing of aradial compressor according to a first example of an embodiment, whereina burst-protection ring is disposed in an annular space which surroundsa compressor impeller installation space; and

FIG. 2 is a schematic axial cross section of a compressor housingaccording to a second example of an embodiment which resembles thecompressor housing in FIG. 1, wherein the burst-protection ring hereforms part of a wall of a spiral duct.

Identical components in the figures have the same reference numerals.Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of embodiments of the present invention.

DETAILED DESCRIPTION

Before describing in detail embodiments that are in accordance with thepresent invention, it should be observed that the embodiments resideprimarily in combinations of apparatus components related to acompressor housing of a radial compressor. Accordingly, the apparatuscomponents have been represented where appropriate by conventionalsymbols in the drawings, showing only those specific details that arepertinent to understanding the embodiments of the present invention soas not to obscure the disclosure with details that will be readilyapparent to those of ordinary skill in the art having the benefit of thedescription herein.

In this document, relational terms such as first and second, top andbottom, and the like may be used solely to distinguish one entity oraction from another entity or action without necessarily requiring orimplying any actual such relationship or order between such entities oractions. The terms “comprises,” “comprising,” or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. An element preceded by “comprises . . . a” does not, withoutmore constraints, preclude the existence of additional identicalelements in the process, method, article, or apparatus that comprisesthe element.

FIG. 1 shows a housing 16 made of three housing components, that is anupper section 10, a bottom section 12, and a middle section 14, for aradial compressor of an exhaust gas turbocharger of an internalcombustion engine, The exhaust gases of the internal combustion enginedrive a turbine impeller which is connected to a compressor impeller notshown in FIG. 1 for co-rotation. The compressor impeller pivots in thehousing 16 around a rotational axis 18 indicated in FIG. 1. The rotationof the compressor impeller aspirates combustion air in an intake tractof the internal combustion engine and compresses it to a higher turbopressure under which the combustion air is supplied to cylinders of theinternal combustion engine

When used herein, terms such as “axial”, “radial”, “circumferentially”,and “in circumferential direction” are to be understood as relative tothe rotational axis 18.

A middle section 14 is disposed between the upper section 10 and thebottom section 12. The upper section 10, the bottom section 12, and themiddle section 14 are made of thermoplastics. Two annular joining areas20 and 22 are formed at the upper section 10. A corresponding end face24 of the middle section 14 abuts on the joining area 20. An end face 26of the bottom section 12 abuts on the joining area 22. The joining area20 and the end face 24 as well as the joining area 22 and the end face26 each form weld zones.

A curvature 28 extending in an annular manner and enlarging incircumferential direction is formed at the upper section 10 in FIG. 1and is open at the bottom. At the radially inside placed end of thecurvature 28 abuts a curved section 32 on a contact area 30. The curvedsection 32 is adapted to the enlarged shape of the curvature 28. It isintegrally molded to the middle section 14. The middle section 14comprises furthermore an axial section 34 with a curve 36 towards aradial section 38. The curved section 32 is integrally molded to thesection 38.

The bottom section 12 is designed substantially as an annular curvature40 that enlarges in circumferential direction. A bushing 42 extendingaxially towards the upper section 10 is attached to the radial exteriorside. The end face 26 is located at the free end of the bushing 42. Anaxial section 44 of the upper section 10 abuts on the internal wall ofthe bushing 42. The housing 16 is in this area double-walled. The bottomsection 12 is—at its bottom side facing away from the upper section10—designed to receive a housing bottom not shown in the drawing.

The curvature 28 at the upper section 10, the curved section 32 at themiddle section 14, and the curvature 40 at the bottom section 12 form aspiral duct 46.

A burst-protection ring 50 which forms a compressor impellerinstallation space 48 is inserted in a force-fit manner to the radialouter wall of the axial section 34. The burst-protection ring 50 is madeof aluminum. The housing 16 is stiffened thanks to the burst-protectionring 50. If parts break away from the compressor impeller, precautionshave been taken by the burst-protection ring 50 which shall prevent thehousing 16 from being penetrated.

The burst-protection ring 50 is located in a circumferential annularspace 52. The annular space 52 is formed between the upper section 10and the middle section 14. The annular space 52 encloses the axialsection 34 radially outside. It is separated from the axial section 34via the wall of the middle section 14 with respect to fluid mechanics.The burst-protection ring 50 is disposed between the compressor impellerinstallation space 48 and the spiral duct 46.

The burst-protection ring 50 features a tubular wall section 54 that iscoaxial to the compressor impeller installation space 48. The wallsection 54 encloses the compressor impeller installation space 48circumferentially in a closed manner. The burst-protection ring 50 isfixed in its position by means of a force-fit connector assembly on theaxial section 34 of the middle section 14 in the housing 16.

For manufacturing the housing 16, the upper section 10, the bottomsection 12, and the middle section 14 are made of synthetic material inseparate processes. The burst-protection ring 50 is made of aluminum asa separate component.

The burst-protection ring 50 is placed in a force-fit manner in axialdirection on the axial section 34 of the middle section 14. In this way,it is secured against loss at the middle section 14. The middle section14 together with the burst-protection ring 50 is inserted in axialdirection into the upper section 10 so that the joining area 20 of theupper section 10 and the joining area 22 of the middle section 14 abuteach other and the contact area 30 of the curved section 32 abutsagainst the end of the curvature 28.

The bottom section 12 is then placed in axial direction on the uppersection 10 so that the end face 26 of the bottom section 12 abutsagainst the end face 22 of the upper section 10. The joining area 20 andthe end face 24 as well as the joining area 24 and the end face 26 arethen welded with each other by means of ultrasonic welding. During thewelding process, the burst-protection ring 50 acts as vibration damping.

The compressor impeller is now disposed in the compressor impellerinstallation space 48 in a manner that is of no interest here.

FIG. 2 shows a second example of an embodiment of a housing 116. Thoseelements that are similar to those in the first example of an embodimentin FIG. 1 have the same reference numerals with the difference that thevalue 100 is added. The second example of an embodiment differs from thefirst example of an embodiment in that the curved section 132 thatdefines also the spiral duct 146, and the radial section 138 are partsof the burst-protection ring 150 instead of being integrally molded tothe middle section 114, as is the case in the first example of anembodiment. The curved section 132 and the radial section 138 areintegrally molded to the side of the coaxial wall section 154 of theburst-protection ring 150 that faces the bottom section 112. Thus, theburst-protection ring 150 also forms the radial wall section 138 of thespiral duct 146.

The curve 136 of the middle section 114 ends in radial directionapproximately at the height of the radial outer interior side of theannular space 152. That end of the curve 136 supports the radial section138 of the burst-protection ring 150 at its backside in radial directionthat faces away from the spiral duct 146. The burst-protection ring 150features between the coaxial wall section 154 and the radial section 138a curve 158 that fits closely to the radial outer surface of the curve136 of the middle section 114.

Furthermore, a plurality of ribs 156 is integrally molded to the radialouter circumferential side of the coaxial wall section 154 and the curve158 of the burst-protection ring 150. The ribs 156 achieve a furtherstiffening of the burst-protection ring 150 and therefore of the housing116.

In all the above described examples of an embodiment of a housing 16;116 of a radial compressor of a turbocharger, the followingmodifications are among others possible:

The invention is not limited to housing 16; 116 of a radial compressorof a turbocharger of a motor vehicle. Rather, it can also be used withdifferent radial compressors, for example with industrial engines.

The terms upper section 10; 110 and bottom section 12; 112 refer only tothe exemplary orientation of the housing 16; 116 in FIGS. 1 and 2. Thehousings 16; 116 can also be oriented differently in the space, forexample such that the upper section 10; 110 is located spatially at thebottom and the bottom section 12; 112 spatially at the top.

Instead of aluminum, the burst-protection rings 50; 150 can also be madeof a different, preferably ductile material, in particular of a metal,synthetic material, carbon fiber, ceramics, aramid fibers or a materialmix.

The burst-protection rings 50; 150 may also be fixed in the housing 16;116 in a different way instead of pressing them on the axial section 34;134. For example, the burst-protection rings 50; 150 may be fixed in thehousing 16; 116 by means of another force-fit connection, a form-fitconnection, for example by means of clamping ribs and/or snap-in hooksand/or beads and/or by means of a cohesive connection, for example bymeans of a glued connection, an injection connection or a weldedconnection.

In the foregoing specification, specific embodiments of the presentinvention have been described. However, one of ordinary skill in the artappreciates that various modifications and changes can be made withoutdeparting from the scope of the present invention as set forth in theclaims below. Accordingly, the specification and figures are to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope of thepresent invention. The benefits, advantages, solutions to problems, andany element(s) that may cause any benefit, advantage, or solution tooccur or become more pronounced are not to be construed as a critical,required, or essential features or elements of any or all the claims Theinvention is defined solely by the appended claims including anyamendments made during the pendency of this application and allequivalents of those claims as issued.

1. A compressor housing (16; 116) of a radial compressor or turbochargercomprising: at least two housing components (10, 12, 14; 110, 112, 114)comprising a molded synthetic material; a compressor impellerinstallation space (48; 148) defined by said housing components andarranged in said housing; a spiral duct (46; 146) defined by saidhousing and arranged within said housing radially spaced outwardly fromand circumferentially surrounding said compressor impeller installationspace (48; 148) relative to a rotational axis (18; 118) of a compressorimpeller; a securement structure (50; 150, 156) circumferentiallysurrounding and enclosing said compressor impeller installation space(48; 148) at least partially in an annular manner, wherein saidsecurement structure (50; 150, 156) is arranged in radial directionbetween said compressor impeller installation space (48; 148) said thespiral duct (46; 146); wherein said securement structure includes aseparate burst-protection ring (50; 150) having a tubular wall section(34; 134) enclosing said compressor impeller installation space (48;148) circumferentially and enclosed completely within said compressorhousing (16; 116), said burst-protection ring (50; 150) with tubularwall section (34; 134) secured in a fixed position within said housing.2. The compressor housing according to claim 1, wherein saidburst-protection ring (50; 150) is arranged within and enclosed withinan annular space (52; 152) defined within said housing, said annularspace surrounding said compressor impeller installation space (48; 148)radially outside, wherein said annular space is defined by and enclosedby at least two of said housing components (10, 14; 110, 114).
 3. Thecompressor housing according to claim 1, wherein said burst-protectionring (50; 150) is securely fixed in position within said compressorhousing (16; 116) by a form-fit connection, wherein said form-fitconnection is any of: by clamping ribs and/or snap-in hooks and/orbeads, and/or by means of a force-fit connection, wherein said forcerfit connection is any of: by pressing on or by pressing in theburst-protection ring, and/or cohesive connection, wherein said cohesiveconnection is any of: a glued connection, an injection connection or awelded connection.
 4. The compressor housing according to claim 1,wherein said tubular wall section (34;134) of said burst-protection ring(50; 150) is made of a ductile material selected from the set consistingof: metal, synthetic material, carbon fibers, ceramics, aramid fibers ora material mix.
 5. The compressor housing according to claim 1, whereinsaid burst-protection ring (150) forms a portion of a wall sectiondefining said spiral duct (146).
 6. The compressor housing according toclaim 2, wherein said burst-protection ring (50; 150) is securely fixedin position within said compressor housing (16; 116) by a form-fitconnection, wherein said form-fit connection is any of: by clamping ribsand/or snap-in hooks and/or beads, and/or by means of a force-fitconnection, wherein said forcer fit connection is any of: by pressing onor by pressing in the burst-protection ring, and/or cohesive connection,wherein said cohesive connection is any of: a glued connection, aninjection connection or a welded connection, wherein said tubular wallsection (34;134) of said burst-protection ring (50; 150) is made of aductile material selected from the set consisting of: metal, syntheticmaterial, carbon fibers, ceramics, aramid fibers or a material mix, andwherein said burst-protection ring (150) forms a portion of a wallsection defining said spiral duct (146).